Most Severe degree of alkalosis occurs in obstruction of -

• Gastric alkalosis is most marked with vomiting due to pyloric stenosis or obstruction because the vomitus is acidic gastric juice only. • Vomiting in other conditions may involve a mixture of acid gastric loss and alkaline duodenal contents and the acid-base situation that results is more variable. • Loss of alkaline small intestinal contents can even result in an acidosis if gastric acid secretion is suppressed.